The pair's marriage has been under the tabloid spotlight for much of this year, amid rumors that the Canadian couple had parted ways.
Despite the speculation, the pair tried to banish the reports by appearing together in August for the first time in months during a trip to a Los Angeles store.
But after Us Weekly magazine reported the marriage was over, Lavigne decided to set the record straight on her MySpace blog.
In a post on Thursday, she wrote, "Deryck and I have been together for 6 and a half years. We have been friends since I was 17, started dating when I was 19, and married when I was 21.
"I am grateful for our time together, and I am grateful and blessed for our remaining friendship.
"I admire Deryck and have a great amount of respect for him. He is the most amazing person I know and I love him with all my heart. Deryck and I are separating and moving forward on a positive note."
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